Silicates containing copper, if heated in the flame in the platinum
forceps, impart a rich green color to the outer flame. In fact, if any
substance containing copper be submitted to the blowpipe flame, it
will tinge it green, provided there be no other substance present to
impart its own color to the flame, and thus modify or mar that of the
copper.

(_d._) _Tellurium._--If the flame of reduction is directed upon the
oxide of tellurium placed upon charcoal, a green color is imparted to
it. If the telluric acid be placed upon platinum wire in the reduction
flame, the oxidation flame is colored green. Or if the sublimate be
dissipated by the flame of oxidation, it gives a green color. If
selenium be present, the green color is changed to a blue.

(_e._) _Zinc._--The oxide of zinc, when strongly heated, gives a blue
flame. This is especially the case in the reducing flame. The flame is
a small one, however, and not very characteristic, as with certain
preparations of zinc the blue color is changed to a bright white. The
soluble salts of zinc give no blue color.

(_f._) _Baryta._--The soluble salts of baryta, moistened, and then
submitted to the reduction flame, produce a green color. The salt
should be moistened, when the color will be strongly marked in the
outer flame. The insoluble salts do not produce so vivid a color as
the soluble salts, and they are brighter when they have previously
been moistened. The carbonate does not give a strong color, but the
acetate does, so long as it is not allowed to turn to a carbonate. The
chloride, when fused on the platinum wire, in the point of the
reduction flame, imparts a fine green color to the oxidation flame.
This tint changes finally to a faint dirty green color. The sulphate